Three unpiloted aerial vehicles of wildly different configurations recently set endurance marks, each a “personal best,” with some achieving world records. The varying designs show what can be achieved by careful aerodynamic design and efficient powerplants. Aerovel Flexrotor Sets VTOL Endurance Mark Not just a fair weather UAV, Aerovel’s unmanned Flexrotor, named for the sea nymph Actaea, “lifted off into a grey and rainy morning with 7.5 kilograms (16.5 pounds) of fuel onboard”. According to the company, “It transitioned from hover to wing-borne flight, and soldiered on through a showery day, a blustery night, and then another day in the breezy and unsettled air behind a cold front. As dusk fell it transitioned back to hover, and dropped gently down onto a 12-foot square helideck underway at 8 [knots] (9.2 mph). Time from launch had been 32 hours and 8 minutes. More than 3 hours’ worth of gasoline remained in the tank.” The press release doesn’t say where the flight took …